In the current energy crisis, strenuous efforts are being made to produce energy without requiring consumption of natural resources. Considerable research and development efforts have been expended in attempts to utilize solar energy and energy generated by wind and water flow. Water wheels and squirrel cage type fans suffer the disadvantage in that only those blades on the side moving with the wind can be utilized, while the blades moving in the opposite direction have to be shrouded. Large propeller type fans rotating in a vertical plane have been tested and tried for production of energy, but they too suffer a number of disadvantages. First, for practical purposes, they must be of considerable diameter for effective energy production. This results in tremendous centrifical forces which may cause vibration and even twisting or crystalization of metal propeller blades and/or destruction of the supporting tower. Even in absence of damage, large propellers tend to be noisy and are, therefore, objectional in a community. Moreover, the large propellers require high towers to provide ample clearance under the propeller tips and such are commonly deemed unslightly and objectionable for community use.